Cathode ray device



Jan. 14, 1936. H. J. MCCREARY cATHoDE RAY DEVICE Filed Jan. 15, 1931Patented Jan. 14,119.36

UNITED STAT-Es PATENT OFFICE 2,027,393 cA'rHonE nar nevica ApplicationJanuary 15, 1931, Serial No. 508,932

\ 18 Claims.

My invention relates in general to 4cathode ray devices, and more inparticular to a cathode ray device in which use is made of the deectionof the cathode ray or beam by an external field. A special object of theinvention is a cathode ray devicein which the cathode ray is deflectedby the earths magnetic iield, the device operating as a compass ordirection indicator.

One embodiment of my invention, which may be termed a cathode raycompass, is illustrated in the accompanying drawing, comprising Figs.

. 1, 2, and 3. Fig. 1 is a plan view, partly in section, showing themechanical construction of the compass, Fig. 2 is a diagrammatic drawingof the electrical circuits involved, while Fig. 3 is a fragmentarydrawing showing the method of suspending the cathode ray tube, a detailwhich does not appear from Fig. 1. j

Referring to Fig. 1, the reference character indicates a base which maybe of wood or other suitable material. Mounted on the base I is abearing member 3. The reference character 5 indicates a platform, whichis secured to a hub 6, the lower end of which is formed into a shaft 4.Suitable roller and ball bearings are provided between the shaft 4 andthe bearing member 3. Thus the platform 5 is supported for rotation onthe base I. A motor 23 is adapted to rotate the platform 5 by means of aworm I8 and a spur gear 1, the latter of which is secured to the hub 6.

Mounted on the platform 5 are two upright standards 8 and 9, Figs. land3. The cathode ray tube 20 is pivotally supported at the upper end ofthese standards. By reference to Fig. 3,

it will be seen that lthe tube 20 is held in a ring or band Ill. Thering I0 has two laterally extending shafts II and I2 which pass throughbearings, in the standards 9 and 8, respectively.

The reference character 2l indicates the elevating motor. By means ofgears I1 and I6 this motor is able to rotate the vertical shaft I5, heldin suitable bearings projecting from standard 8. Shaft I5 carries a wormI4 which meshesA with the spur gear I3. The latter is secured to shaftI2, from which it will'be evident that rotation of the gear will rotatethe band I0 to elevate or lower the upper end-of' the cathoderay tube2li depending on the direction of rotation. V Referringto Fig. 2, thecathode ray tube 20 comprises a glass envelope, a hot cathode 30, a

perforated shield 3l, an anode 32, and a plate or target 35 againstwhich the cathode ray impinges. In general the cathode ray tube maybe ofthe usual construction. It is desirable, how- (ci. ss-,zon

ever, to make the openings inthe shield 3| and anode 32 larger thanusual so as to secure a good sized ray or beam. With an opening onefourth inch in diameter a ray carrying one milliampere can be obtained.The target 35 is suit- 5 ably secured in the end of the tube oppositethe cathode. This target comprises four segments, 36, 31, 38, and 33,which are insulated'from each other. Each segment has a separatetermina! wire extending outside the tube. lo

For the purpose of controlling the elevating motor 2| there is provideda polar relay 40 and relays 46 and 41. The rotating motor 23 iscontrolled by means of a polar relay and relays 64 and 65. Current issupplied by batteries B, 15 B1, and B2. p

The necessary circuit connections between the base and the apparatusmounted on the rotatable platform 5 are taken through slip rings andbrushes, so as to permit unlimited rotation of the 20 platform.Referring to Fig. y1, a cylindrical block of insulating material 25encircles the bearing member 3 and has embedded in its surface. a seriesof slip rings 23. Ambrush holder 2B is secured to the gear 1, andcarries a series of spring 25 actuated brushes Z'I'Which bear on therings 26. An opening 34 drilled in the block 25 permits conductors to be`connected to the slip rings 26. These conductors may be taken through aconduit 83 to the box 24. -This latter may lcon- 30 tain the batteriesand the relays 60, 84, and 65. Italso 'serves as a support for the motor23. Suitable conduits such as 80, BI, and B2 may also be provided forprotecting the conductors leading to and connecting together theapparatus mount- 35 ed on the platform 5. The box 22 contains the relays44, 4,8, and 41.

The conductors connecting to thewtube 20 are taken through condult'l andare preferably flexible leads which extend from theend of the con- 40duit to the terminals of the tube. These leads should be long enough toprovide for a considerable range of movement of the tube. It may bepointed out that the compass herein described specifically is notintended to provide for an un- 45 limited movement of the tube about ahorizontal` axis because in most commercial uses, such as on ships orairplanes, such movement is not required. In certain cases. however, asin the case of a military or stunting plane, an unlimited 50 rotation ofthe tube about its horizontal axis may have `to be provided for. 'I'hiscan readily be done by using a system of brushes and slip rings, such asare shown for carrying the electrical connections between the platformand the base. u

- and 51.

The operation of the cathode ray tube in producing the cathode ray needs`no extended explanation. Current for heating the cathode 3|)y issupplied by battery B, which is connected by a pair oi' slip rings andbrushed to conductors 56 These conductors also supply current frombattery B for operating relays 46, 41, 64, and 65, and the motorsr 2|and 23. The proper accelerating potential is supplied to the anode 32 bybattery B1, which is connected through a slip ring and brush toconductorI 58. The standards 8 and 9 and other parts near the cathoderay tube should be made of non-magnetic material.

The operation of the compass will now be described, it being assumedthat the device is mounted in an airplane. The base is suitably securedin the cockpit of the plane in a horizontal position, and the circuitsare connected up as shown in Fig. 2. It may be pointed out now that theprinciple of operation is to maintain the cathode ray beam parallel tothe lines of force of the earths magnetic field. 'I'his is accomplishedlby rotating the platform 5 or by changing the elevation of the tube 20,or both, depending on the movement of the plane.

. VHThe operation will be explained herein on the the cathode endpointing to the north. In the l northern hemisphere the lines of forceof the earths field make an angle with the surface of the earth the apexof which is toward the north. The amount of the angle, of course,depends on the latitude. The position of the tube, therefore, will besomewhat as shown in Figs. 2 and 3, the exact angle of inclinationdepending on the latitude of the plane.

For convenience it may be assumed that the plane is traveling due south.The tube points south and the cathode ray, which is parallel to theearths field, impinges on the center of the target 35. This is thenormal position of the beam. If the beam is small enough it will impingeon insulating material at the center of the target and little or nocurrent will fiow through relays 40 and 60. However, the beam may belarge enough to impinge simultaneously on segments 36, 31, 38, and 39 ofthe target, but this produces no effect because the relays 40 and 60 aredifferentially wound as will appear presently.

Suppose now that the plane noses down toward the earth. This causes thecathode ray to cut the earths field, with the result that it isdeflected to the right and impinges equally on segments 31 and 38 atsome distance from the center of the target. A circuit is thusestablished which includes the cathode 30, cathode ray, segments 31 and38, windings 42 and 43 of polar relay 40 in parallel, conductors 54 and55 in parallel, brushes 21, slip rings 26, windings 6| and 62 ofl polarrelay 60 in parallel, and the batteries B2 and B1 in series. Thewindings 6| and 62 of relay 60 oppose each other and the relay is notoperated. Windings 42 and 43 of polar relay 40 assist each other and therelay is operated to close a circuit for relay 46 in an obvious mannerby means of armature 45. Upon energizing relay 46 closes a circuit forthe armature winding of motor 2| at armature 50, and at armatures 48 and49 it closes a circuit for the field winding of the motor. The motor 2|,therefore, starts up and rotates in such a direction as to elevate thetarget' end of the tube. As the tube is elevated the point at which thecathode ray impinges the target moves back toward the center of thetarget. When the tube is once more parallel to the earths field thepoint of contract with the target will be at the center and relay 40will release its armature. This breaks the circuit of relay 46 whichdeenergizes and stops the motor 2|.

Suppose now that the plane noses upward. 'Ihis deects the beam to theleft, causing it to impinge on segments 36 and 39. A circuit is thusestablished which includes segments 36 and 39, and windings 44 and 4| ofpolar relay 4|), the l remaining elements of the circuit being the' sameas previously explained. Relay 60 remains inactive as before, but relay40 is operated, its

at armature 53 closes a circuit for the armature` winding of motor 2|and at armatures 5| and 52 closes a circuit for the field winding of themotor. The field is connected up reversed and the motor now runs in theproper direction to lower the target end of the tube. When the necessarycorrection is made the ray will once more contact the target at thecenter, the relays 40 and 41 will fall away and the motor 2| will stop.

It will now be assumed that the plane turns to the left. As a result thecathode ray is deflected downward, so that it impinges on segments 38and 39. A circuit is, therefore, established which `includes the cathode30, the cathode ray, the

segments 38 and 39, windings 42 and 4| of polar relay 40 in parallel,conductor 54, a brush 21 and a slip ring 26, winding 6| of polar relay60, and batteries B2 and B1. Windings 4| and 42 of polar relay 40 opposeeach other and relay 49 is not operated. Relay 60 is operated and itsarmature 63 closes a circuit for relay 64, which in turn closes circuitsfor the armature and eld windings of motor 23. The motor now starts upand rotates the platform 5 in such a direction as to turn the tube 2|Jtothe right, thereby bringing the tube back parallel to the earths field.The point of contact with the target moves up to the center of thetarget, relays 68 and 64 are deenergized, and motor 23 stops.

If we assume now that the plane turns to the right, the cathode ray willbe deected upward and will impinge on segments 36 and 31. Thisestablishes a circuit similar to the one previously traced except thatit includes windings 43 and 44 of relay 40 and winding'62 of relay 60.Relay 40 does not operate because windings 43 and 44 oppose each other.Relay 60 operates and now closes a circuit for relay 65. The latterrelay starts the motor 23, but since the field is connected up reversed,the motor runs in the opposite direction from what was the case before,and turns the platform 5 in a counter-clockwise direction so as to turnthe end of the tube 2li to the left. When the necessary correction hasbeen made the ray will once more engage the center of the target, andrelays 60 and 65 will deenergize to stop the motor.

In the foregoing, simple movements of the plane have been considered forconvenience in explaining the operations which take place in maintainingthe axis of the tube parallel to the earths field. It will be clear,however, especially in the case of an air plane, that compounddirectional changes may take place. For instance, the plane may nosedownward and at the same time turn to the left. This causes the cathoderay to impinge on segment 38. A circuit is thus established whichincludes winding 42 of polar relay 49 and winding 6| of polar relay 60.By the operation of these tworelays, motors 2| and 23 are operatedsimultaneously to increase the `eletarget toward the center. In case thechange of i direction to the left was relatively small, however.

the correction for this change will be accomplished rst and the point'of contact with the target will be brought to the dividing line betweensegments 31 and 38. Segment 31 is now rendered active, as well as,segment 38. As aresult winding 43 of relay 40 and winding 62 of relay B0are included in the circuit. This deenergizes relay 60 to stop the motor23, but relay 40 remains en-J ergized and motor 2| continues runninguntil the beam reaches the center of the target. The operations whichtake place in the even of other changes in direction may readily bededuced from the foregoing and it will be unnecessary to further extendthe explanation. Suffice it to say that the axis of the tube ismaintained -parallel to the lines of force of the earths eld at alltimes, except for momentary displacements which take place when theplane changes direction, which are promptly corrected for.

Since the tube points in one direction continually, that is, to thesouth, it constitutes a compass or direction indicator. The direction inwhich the plane is traveling may be noted directly by observing theposition of the tube, and in some cases this is accurate enough. Ifdesired, however, the entire apparatus may be enclosed in a containerhaving a dial forming the top thereof. A forked shaft may be secured tothe standards 8 and 9 and extend upward `through the cover of thecontainer at the center of the dial. This arrangement will give a moreaccurate reading and at the same time the parts will be protected frominjury. The dial and pointer may also be located at some distance fromthe apparatus with a shaft and gears connecting the pointer with theshaft 4 so that the two will move in synchronism.

f It will be apparent that in some situations the compass will notrequire an elevating mechanism. When the only directional changes whichtake place are such as can be corrected for by rotation of the device,the segments 36 and 31 may be united, as .are segments 38 and 39. Theresulting half discs are connected'-` directly to a polar relay such as60, relay 40 and the associated apparatus being omitted. It may be notedalso that the apparatus may be used to measure the inclination of thelines of force of the earths field to the surface of the earth at anypoint. Other modifications and uses are within the scope of theinvention.

I do not wish to be limi-ted, therefore, to the precise structure shownand described herein but desire to secure by Letters Patent all formsand modifications of my invention which are covered by the appendedclaims.

I claim:

1. In a compass, means for producing a cathode ray, a movable member,and means controlled by the ray for maintaining said member parallel tothe lines of force of the earths field, said last means includingmechanism for moving said member to correct for angular displacement inboth vertical and horizontal planes.

2. In a compass, a cathode ray tube, and means for automaticallymaintaining the axis of said tube parallel to the lines of force of theearths eld, said'means comprising mechanism responsive to deflection ofthe ray when it cuts the eld.

3. In a compass, a support, a cathode ray tube mounted on saidlvsupport,'means for moving the tube relative to said support intwo-different planes, and circuits including said ray'and estab- Ylished responsive to deflection of the ray when'the v position of lthesupport is altered relative to a magnetic field for controlling saidmovingmeans go 1rtiiaintain the said tube in fixed relation' to said 4.In combination, a cathode ray tube having its axis normally in agivenposition, and means responsive to the deflection of the ray by a fieldof force when the position of the tube is'changed relative to said fieldfor restoring said tube to its original position.

5. In combination, a cathode ray tube, a circuit completed by deflectionof the ray by a eld of force when the tube is moved in a direction suchthat the ray cuts said field, and means controlled over said circuit formoving the tube in another direction.

6. In combination, apparatus for generating a cathode ray and located ina magnetic field, a circuit completed by deflection of the ray when theposition of said apparatus relative to the field is changed, and meanscontrolled over said circuit for restoring said apparatus to its initialposition.

7. An instrument comprising means for generating a cathode ray, areference member, a member angularly movable with respect to saidreference member, and means responsive to deflection of said ray whensubjected tothe earths eld for positioning said second member toindicate the inclination of the earths field with respect to saidreference member. Y

8. An Iinstrument comprising means for generating a cathode ray, amovable member, means for positioning said member at different angles tothe surface of the earth, and means responsive to deflection of said raywhen influenced by the earths field for controlling said positioningmeans.

9. A climb and dive indicator for aircraft, for use on courses which arenot substantially normal to the lines of force of the earths field, saidindicator comprising indicating means, means for producing a cathoderay, means for operating said indicating means, and means including acircuit completed by deflection of the cathode ray by the earths fieldfor controlling said operating means.

10. A compass for indicating direction toward `or away from the surfaceof the earth, said compass comprising a movable member, means for movingsaid member to maintain it at a known angle to the earths surface, meansfor producing a cathode ray, and means controlled by said cathode raydue to a change in its position in the earths field for controlling saidmoving means.

11. A compound compass for indicating direction in two different planes,said compass comprising a cathode ray tube, means for positioning saidtube in both said planes, and means responsive to deection of the ray bythe earths field for controlling said positioning means to restore theray to underlected position.

12. An instrument comprising a cathode ray tube, means for moving saidtube in two different planes, and means responsive to deflection of theray by an external eld for controlling said moving means.

13. In combination, a support, a cathode ray tube rotatably mounted onsaid support, rotatingk means for said tube, and means for operatingsaid rotating means-responsive to deflection offsaid ray by a magneticfield.

14. In a compass, a main supporting member, a cathode ray tube mountedthereon, mechanism for moving said tube relative to said member, andmeans controlled by deflection of the ray when the compass is movedrelative to the earths iield for operating said mechanism to restore theray to undeected position.

15. -In combination, a cathode ray tube, a circuit completed bydeflection of the ray by a. field of force when the tube is moved in adirection such that the ray cuts said field, and means controlled oversaid circuit for producing further movement of said tube.

16. An instrument comprising means for generating a cathode ray, ahorizontal member, a member movable about a horizontal axis, means foi`supporting said axis adjacent said horizontal member with the secondmember at a variable angle thereto depending on its position on saidaxis, and means responsive to deflection of said ray by the earthsmagnetic field for moving said 'second member on said axis to indicatethe inclination of the earths field with respect to said horizontalmember.

17. An instrument comprising means for generating a cathode ray, amember angularly movable relative to the surface of the earth, andmeansrgntrolled by deflection of said ray by the earths field forpositioning said member by angular movement thereof to indicate theinclination of the earths eld where 'the instrument is located.

t" 18. In combination, apparatus for producing a and means controlledover said circuit for restori ing the relation between the tube andfield so that the latter is not cut by the ray.

HAROLD J. MCCREARY.

